Beijing has faced mounting global criticism over its construction on the Spratly Island archipelago, a group of largely low-lying sandbars and reefs scattered across a region claimed by China, Vietnam, Taiwan, Brunei, Malaysia and the Philippines.

Diplomats believe the ultimate purpose is to create structures that can serve as viable forward operating bases for Chinese military manoeuvres during future military spats.

But Beijing said yesterday that its land reclamation of disputed reefs was “beyond reproach”, and “within the scope” of sovereignty.

It comments followed concerns voiced by Mr Obama on Thursday that China is not abiding by international rules and norms in the South China Sea, adding the country’s “sheer size and muscle” could force other nations into subordinate positions.

“Just because the Philippines or Vietnam are not as large as China doesn’t mean that they can just be elbowed aside,” he said at a town hall event in Jamaica on Thursday, according to Reuters.

Though various countries have built on their Spratly claims in the past, the speed and scale of China’s recent efforts has caused alarm.

Foreign ministry spokesperson Hua Chunying said on Thursday that such activities were “beyond reproach”.

She added that the government has been carrying out construction work to “improve the living and working conditions” of personnel stationed there and to “better safeguard national territorial sovereignty”.

The construction would also allow China to better meet obligations such as disaster mitigation, scientific research and navigation safety, Ms Hua added.